Hitachi 7K100 Hard Drive Specifications - Page 46
Acoustics - specs
UPC - 683728198671
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The shocks are applied for each direction of the drive for three mutually perpendicular axes, one axis at a time. Input levels are measured on a base plate where the drive is attached with four screws 6.6 Acoustics 6.6.1 Sound power levels The criteria of A-weighted sound power level are described below. Measurements are to be taken in accordance with ISO 7779. The mean of the sample of 40 drives is to be less than the typical value. Each drive is to be less than the maximum value. The drives are to meet this requirement in both board down orientations. Table 23: Weighted sound power A-weighted sound power Typical (Bels) Idle 2.6 Operating 3.0 Maximum (Bels) 2.9 3.5 The background power levels of the acoustic test chamber for each octave band are to be recorded. Sound power tests are to be conducted with the drive supported by spacers so that the lower surface of the drive be located 25±3 mm above from the chamber floor. No sound absorbing material shall be used. The acoustical characteristics of the disk drive are measured under the following conditions: Mode definitions • Idle mode: Power on, disks spinning, track following, unit ready to receive and respond to control line commands. • Operating mode: Continuous random cylinder selection and seek operation of the actuator with a dwell time at each cylinder. The seek rate for the drive is calculated with the following formula: Ns= 0.4/(Tt + T1) where: Ns = average seek rate in seeks/s Tt = published seek time from one random track to another without including rotational latency T1= equivalent time in seconds for the drive to rotate by half a revolution 6.6.2 Discrete tone penalty Discrete tone penalties are added to the A-weighted sound power (Lw) with the following formula only when determining compliance. Lwt(spec) = Lw = 0.1Pt + 0.3 < 4.0 (Bels) where Lw = A-weighted sound power level Pt = Value of desecrate tone penalty = dLt - 6.0(dBA) dLt = Tone-to-noise ratio taken in accordance with ISO 7779 at each octave band Travelstar 7K100 Hard Disk Drive Specification 32